Installed 2.5inch readylift leveling kit. Got 35x12.5r20 procomp xtreme at's. Before spacers it barely cleared upper control arm and they started to rub the sides of the upper control arm at about 90percent of a full turned wheel and at full turn they rubbed sway bar. Put on spacers and crawled under the truck while son was turning the wheels both ways and no rubbing. it comes close to the upper control arm on the sides but you can see daylight, although not much. I have stock 20's but i think they are the old 20's from 2005 or so but the backspacing i believe is the same as the newer ones.
For future searches with the question of will they fit:
a 2007 dodge ram 4x4 with a 2.5 inch level kit and 1/4 inch spacer will fit with no rubbing or cutting sporting 35x12.50r20's.